Ship&#39;s hull



Nov. 28, 1961 L. COSTA ETAL 3,010,419

SHIP'S HULL Filed Dec. 24, 1957 2 Sheets-Sheet 1 jm/emon' L80 Costa,

Jo/m i G: /zumadxer Nov. 28, 1961 L. cosTA ET AL 3,010,419

SHIPS HULL Filed Dec. 24, 1957 2 Sheets-Sheet 2 Inventor? LEO CosZZz,

John H. GScbumacfier United States Patent Ofiice 3,010,419 Patented Nov. 28, 1961 3,010,419 SHIPS HULL Leo Costa, Geneva, Switzerland, and John H. G. Schumaeher, Bremen, Germany, assignors to Maierform Holding S.A., Geneva, Switzerland Filed Dec. 24, 1957, Ser. No. 704,957 2 Claims. (Cl. 114-56) This invention relates to a ships hull, and more specitically to a hull for fast sea-going vessels, such as sea rescue boats, requiring good stability in rough seas and in surf.

It is an object of the invention to provide a hull permitting high speeds of propulsion in calm as well as in rough seas.

It is another object of the invention to provide a hull having good maneuverability, stability of course, and seaworthiness.

It is a further object of the invention to provide a hull having a large displacement relative to its length, breadth, and depth, and capable, therefore, of being solidly and heavily constructed.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings in which like reference numerals designate like lines throughout the figures thereof, which are design drawings of the type customary in naval architecture and wherein:

FIG. 1 is a sheer plan of an embodiment of a hull of the invention.

FIG. 2 in its upper portion is a half breadth plan of the hull of FIG. 1, and the lower portion of FIG. 2 illustrates a diagonal.

FIG. 3 is a body plan of the hull of FIG. 1, and

FIG. 4 is a fragmentary detail of a frame in the midship section of the hull of FIG. 1.

In the sheer plan or side elevation of FIG. 1, the several water lines are indicated in the customary manner by Arabic numerals 15 from the keel upward, the load water line at which the ship will float at nominal design displacement being further indicated by line L.W.L.- L.W.L. Twenty-one equally spaced stations, not all of which are actually drawn, are indicated by Arabic numerals -20 from the stern to the stem. Contour lines indicated by dash-dot lines and by Roman numerals I to III indicate the shape of the hull at various distances from the central plane of symmetry.

The half-breadth plan in the upper half of FIG. 2 shows the form of the hull at the several water lines, supposing it to be cut by horizontal planes at the levels of these lines. The contour lines I to III and square stations 0-20 appear as straight lines intersecting at right angles. The lower half of FIG. 2 is a plan view of the diagonal plane S of FIG. 3.

The body plan of FIG. 3 illustrates the sectional form of the hull at the square stations supposing it to be cut by transverse planes at these stations. The square stations of the fore body are illustrated in the conventional manner in the right half of the body plan, the square stations of the after body in the left half. The body plan furthermore indicates the position of a diagonal plane S which is seen in plan view in the lower portion of FIG. 2.

FIG. 4 shows part of the contour of a frame in the midship section of the hull having a downward concave bottom between keel and bilge, the depth of concave curvature being indicated at e between two arrows.

All lines in the several figures represent the intersections of planes with the surface of the framing of the ship.

As shown in FIGS. 1, 2 and 3 of the drawings, the hull of the invention is built up on frames which from the bow frame towards the midship section show a gradual transition in form. The foremost frame is sharply V-shaped at the bottom adjacent to the keel, the bottom members of the frame forming a sharp acute angle, and the frame flares out broadly above the water-line towards the deck. From the stern towards the midship section the bottom angle of the frames gradually becomes wider and the change of frame contour becomes relatively rapid starting at about one-fifth of the ships length aft of the stem, leading to a midship section of frames which may be of conventional shape with a rectilinear bottom contour between keel and bilge. The frames preferably are of a downward concave contour between keel and bilge as illustrated in FIG. 4 by the two arrows, thus preparing the flow of the water into the stern channel formed by the arched bottoms of the frames in the aft-section of the hull.

This arrangement of the frames of the forebody results in submerged Water lines having an S-shape of more or less pronounced curvature. A substantial portion of the bow wave and wake is sucked under the hull because of the shape of the midship section and is conducted towards the ships screw.

A bow configuration of the hull as shown in FIG. 1 and apart from FIG. 3 would in an otherwise conventional hull generate a high bow wave and heavy wake at any substantial speeds. But the formation of such a wave is largely reduced by the special contours of the frames illustrated in FIG. 3, and the wave extends almost to the main frame, particularly at high Froudes numbers (speed-to-length ratios); The wave is compressed by the special shape of the midship section and is conducted thence to one or several channels below the after body of the hull. The after body is designed with a stern channel to permit maximum speed in rough seas. Such a design gives excellent sea-worthiness to boats of small or medium tonnage. The corresponding form of the frames is readily apparent from FIGS. 2 and 3.

FIG. 2 especially shows the relatively severe S-shaped curvature of the submerged waterlines 1, 2 and 3 which is characteristic for the shape of the submerged portion of the V fore body of the invention.

The body plan of FIG. 3 illustrates the combination of the various frame shapes in the fore and after sections of the hull. The bottom members of the frames nearest the stern meet at the keel at a very acute V-angle and sharply flare out from the water line L.W.L. towards the deck line, the radius of curvature r of the flaring portion central plane of the hull gradually increases to approxi-.

mately 30, and the radius of curvature of the frame portions above the water line L.W.L. increases correspondingly, as shown in FIG. 3. Going from stem towards stern, the sides of the frames gradually flatten out so that they approximately are straight above the water line L.W.L. at square station 15. They are then increasingly curved concavely towards the plane of symmetry of the hull, and show a gradual transition to the rounded shape of the midship section. At the midship section the bottom members of the frames gently rise from keel to bilge with a concavely downward curvature. The amount of curvature is indicated at e in FIG. 4.

The frames of the aft section are very shallow and are sharply knuckled along line b so as to define a stern channel. We prefer to provide a flat bottom section in the aftmost frames as indicated by line d in FIG. 3.

The diagonal plane S shown in FIGS. 2 and 3 defines the approximate location of the areas of greatest curvature in the frames of the-hull and particularly of the forebody. The area of greatest curvature of the frames at least in the forebody should lie at or near the intersection of diagonal plane S with the surface of the framing of the hull. The position of diagonal plane S is defined by two parallel lines D and K (FIG. 3), D extending horizontally in the plane of symmetry of the hull from the point where the plane of symmetry intersects the underside of the deck at the bow, and K, being parallel to.

the plane of symmetry at a distance equal to the half beam of the hull at a depth below the water line L.W.L. of one-half of the draft T of the hull. For the purpose of determining the position of lines D and K, the hull is defined by the outside of the framing. The lines are indicated in FIG. 3 by their points of intersection with the plane of the body plan.

Boats even if of considerable beam, when equipped with the hull of the invention, have exceptional stability and maneuverability and can be used safely in rough seas, in ground swells, and in heavy surf. This type of boat is therefore especially suited for sea rescue operations of all kinds. It is fully capable of meeting all the requirements for the rescue of ship or airplane crews on the high seas and in all coastal waters under all weather conditions. Boats having hulls according to the present invention are equally well suitedfor such special vessels as coast guard boats, customs launches, and police vessels. A boat whose hull combines the various advantageous features disclosed herein is a speedy utility vessel for all-weather service.

Extensive tests performed on models in an experimental tank have proved the power savings resulting from the special shape of the hull and from the possibility of advantageously utilizing part of the wake and conducting it to the channels formed in the stern portion. 'By sucking oil? a part of the bow wave, as described hereinbefore, the water resistance of the hull is offset to a certain extent. The seaworthiness of the hull of the invention was successfully tested with a full-scale experimental boat traveling in extremely heavy seas.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

What we claim is: V

1. A ships hull comprising a plurality of frames, the bottom members of the frames in the -bow of said hull forming a sharp acute angle at the keel, which over the first tenth of the hulls length 'abaft of the bow form an angle of less than 30 with the plane of symmetry of said hull, said members rising substantially straight from the keel to the water line and flaring out broadly between the water line and the deckline of said hull with an ample radius of curvature, the bottom members of said frames in the midship section being designed to lead downwardly from the bilge to the keel and being curved concavely downwardly to said keel, said bottom members of the frame in midship section being further shaped for initiating channel formation toward the stern of the hull, and the frames in the aft section being very shallow and sharply knuckled above the keel, whereby said channels are more sharply defined at the stern of the hull.

2. The invention according to claim 1 further including said frames positioned adjacent the stern portion of the hull being substantially completely fiat.

References Cited in the file of this patent UNITED STATES PATENTS 1,010,053 Hunter N0v..28, 1911 1,060,985 Von Koppen May 6, 1913 1,864,102 Telfer June 21, 1932 2,185,430 Burgess Ian. -2, 1940 2,342,707 Troyer Feb. 29, 1944 2,599,163 Costa June 3, 1952 FOREIGN PATENTS 727 Great Britain 1912 13,074 Great Britain 1909 764,204 Germany May 26, 1955 873,668 France Jan. 27, 194-3 

